The present invention relates to the field of vehicular fuel storage and supply systems and more particularly to replaceable fuel systems for alternative fuels such as compressed natural gas (CNG), hydrogen, and liquefied natural gas (LNG).
Typically, on-board vehicular fuel supply systems comprise one or more fuel tanks integrated into the chassis of a vehicle. Installation of the fuel system is a part of the vehicle""s basic construction and is typically performed in assembly-line fashion at the factory.
Fuel systems such as described in U.S. Pat. No. 5,794,979 to Kasuga et al. are designed for alternative fuels such as CNG or LNG where a plurality of compressed pressurized fuel cylinders are mounted in a vehicle. A tank supporting frame, installed complete with the fuel tanks and associated pipes and seals, is preferably installed through a rear window opening, during initial manufacture of the vehicle. The frame, following insertion into the fuel storage envelope in the vehicle, is subsequently bolted to the car body and the ends of the pipes connected to the ends of the fuel lines on the car body. Once installed in this fashion, the fuel system becomes an integral part of the vehicle body and cannot be readily removed for inspection, repair or replacement.
Malfunction in any part of the system results in costly repair and significant down-time as the vehicle must be removed from the road. Costs escalate with increasing time to disassemble portions of the vehicle to gain access to the system, perform repairs and reassemble the vehicle.
U.S. Pat. No. 5,997,040 to Fukagawa et al. teaches a modularized and compact fuel system comprising a support frame bolted to the car-body side supporting frame, a single fuel cylinder secured to the support frame using belly straps and a joint box for connection of the fuel and fill lines from the tank to the lines of the vehicle. The frame taught in Fukagawa is not readily adapted to secure more than one fuel cylinder nor is there any indication that fuel lines from a plurality of fuel cylinders could be integrated into the joint box provided. Fukagawa teaches additional side frame components being bolted first at each side of the car body prior to installation of the module. The fuel tank attached to the remaining portion of the frame is then inserted into the car body through a rear door and moved rearward between the wheel housings to align with the side frame component. Once aligned, the module is bolted into place. If maintenance is required, the reverse steps are performed including un-bolting all the fasteners for lifting the module free of the vehicle. Fukagawa avoids multiple vessels so as to ensure a compact module for ease of installation. A larger vessel or a plurality of vessels are not contemplated.
Where a plurality of vessels is required to increase the capacity of the system, the single vessel system of Fukagawa is no longer applicable.
Clearly there is a need for a lightweight fuel system comprising a plurality of pressurized fuel cylinders held together in a unitary structure complete with piping and valves that can be safely secured to the body of a vehicle when in use, but be readily removable for service. Securing means that can be readily released, combined with removable piping connections would allow the entire fuel system to be removed from its permitted dimensional fuel storage envelope in the vehicle for inspection or servicing. Further, a modular system could be replaced even on site, as a single module, should it malfunction. Swapping of a replacement module for the faulty module permits rapid repairs and also avoids unnecessary delays.
The present invention overcomes the prior art requirement for labor intensive and costly servicing, inspection or replacement of a fuel system. A lightweight, unitary fuel system module is provided that can be quickly and removably secured to a vehicle body. The module is easily unlatched from the body and, with minimal detachment of piping connections, can be partially or completely removed, as a complete module, from the vehicle for inspection, repair or reinsertion. Should the module require unknown or extensive repair or component replacement, the entire used module can be replaced by a second replacement module to minimize on-road time losses.
In a broad aspect of the invention, a modular fuel system is provided for a vehicle having fuel lines and a fuel storage envelope, the fuel system comprising:
one or more pressurized fuel cylinders;
a frame in which the one or more fuel cylinders are mounted to form a replaceable module; and
a latching mechanism attached to the frame and adapted for cooperating with anchors in the envelope for releasably securing the frame within the vehicular envelope and operable between a first secured position and a second released position.
Such replaceable modules are self supporting during removal and replacement steps. Preferably, each fuel cylinder has a longitudinal axis and opposing neck ends, the opposing neck ends of each of the one or more fuel cylinders being neck-mounted to the frame. The fuel cylinders, associated instrumentation and tubing are secured to the frame for insertion into the vehicle as a unitary module.
In a preferred embodiment of the invention, the fuel cylinders and associated tubing are housed in a mounting frame comprising at least two end brackets. The brackets are lightweight and designed to permit neck-mounting of each fuel cylinder at opposing neck ends. The frame is secured to the structure of a fuel storage envelope within the vehicle using a releasable latching mechanism capable of safely securing the frame under crash loading. Further, the frame is fitted with means to allow easy removal of-the-system-as a module, such as roller wheels or cooperating Teflon slides.
Preferably, the fuel cylinders are lightweight fiber reinforced, aluminum-lined fuel cylinders having opposing neck-ends, capable of storing pressurized fuel gas such as hydrogen. Instrumentation associated with delivery and monitoring of fuel is provided. Three lines of pressure tubing are typically used for connecting the fuel cylinders to the vehicle; a filling line, a fuel line and a venting line. Each line is housed within a mounting frame for connection to the fuel cylinders, in parallel. The fueling lines converge at a periphery of the frame for ease of connection to the vehicle. Removable fittings join the three lines to corresponding lines on the vehicle body. More preferably, the frame further comprises crossbeams for additional structural rigidity and for attachment of the latching mechanism to the underside of the frame. With pressurized fuel cylinders, the neck-mounting attachments are preferably adapted to permit some longitudinal expansion at least atone neck-mount.
In another aspect of the invention, a method for removal and replacement of a used module of the present invention from a vehicle fuel storage envelope is provided, the method comprising the steps of:
providing at least two modules, a used module and a replacement module, each module having one or more fuel cylinders mounted to a frame, the frame having a latching mechanism for securing the mounting frame to the vehicular envelope;
disconnecting means for fluidly connecting the pressurized fuel cylinders with fuel lines in the vehicle;
actuating the latching mechanism of the used module from a first secured position to a second released position; then sequentially
removing the used module from the vehicle""s envelope;
inserting a replacement module into the vehicle""s envelope; and then
actuating the latching mechanism of the replacement module for securing the mounting frame to the vehicle from a second released position to a first secured position; and
reconnecting the means for fluidly connecting the pressurized fuel cylinders with the fuel lines in the vehicle.
The method is particularly convenient when two or more fuel cylinders are involved in the module.